An owner brings a young cat into my clinic. The cat’s been off her food for a few days, has a dull unkempt coat, and is running a fever. Something clicks and the thought “FIP” pops into my head. I take a history, hoping for a simple explanation, such as the cat got into a fight…but, no, she’s strictly indoors and an only pet…and the suspicion of FIP ratchets up a notch.
As a vet, feline infectious peritonitis (FIP) is a condition which leaves me feeling rather helpless because there is no effective treatment (Interferon therapy offers a glimmer of hope, but is not proven.) But before I get carried away, let’s start at the beginning with some facts about FIP.
What is FIP?
FIP does what is says on the label. Decode “FIP” and you understand what it is:
Feline = cat
Infectious = passed between patients
Peritonitis = inflammation of the lining of the abdomen (tummy) and often accompanied by a build-up of fluid
In other words FIP is an infectious condition passed between cats and which causes fluid to build-up in the tummy.
The cause of the infection is a coronavirus…but this is where things stop being simple and quickly get complicated. Remember that name, coronavirus, because we’ll come back to it later.
What are the Symptoms of FIP?
FIP is most common in young cats, under the age of two-years. The virus can be fought off by a strong immune system, but those with a weaker immune system such as the young or elderly (classed as cats over 11-years of age) and somewhat bizarrely, Burmese cats, are most at risk. The Burmese predisposition for FIP isn’t understood, and no-one knows why this should be the case.
FIP takes one of two forms: wet or dry; of which ‘wet’ has more obvious symptoms and kills more quickly, within a matter of weeks. The ‘wet’ form gets its name because fluid builds up in the abdomen, causing a marked potbellied appearance. Whereas the dry form doesn’t produce fluid and the cats survive for a few months.
The symptoms are quite vague and in the early stages can easily be mistaken for the after effects of a cat fight. These include:
- Being off colour
- Decreased appetite
- A dull, starry coat
- Weight loss
- A fever
- Diarrhoea
In the later stages, other signs develop such as:
- Fluid in the chest or belly (with laboured breathing)
- Iritis (inflammation of the iris or coloured part of the eye)
- Deposits in the front chamber of the eye
- Anaemia
- Jaundice
- Poor co-ordination
- Seizures
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How do Cats Catch FIP?
Coronavirus causes FIP, but (and it’s a big ‘but’) not all cats with coronavirus will develop FIP. Time for some statistics:
- Stray cats – 4% have detectable antibodies against coronavirus (in other words they ‘test positive’ for coronavirus)
- Cats in breeding catteries – around 53% test positive
- Show cats – 82% test positive
BUT
- Only 10% of these cats go on to become sick with FIP.
The reason for this is that coronavirus has a split personality. There is the first persona, of a common virus which causes harmless, self-limiting diarrhoea; and the second persona is the mutated form of the virus which causes FIP.
To mutate, the coronavirus needs contact with lots of cats, because each time it infects a new cats it mutates a little. Once the virus reaches a critical level of change, it turns into something altogether more sinister and serious.
Those cats most at risk are those who share litter trays in a multi-cat household, hence the high level of coronavirus in breeding establishments (kittens sharing trays with the mother) and amongst households of show cats.
This also has the unfortunate implication that when you buy a purebred kitten from a breeder with several queens, there is a chance the kitten may already have coronavirus and it’s a lottery as to whether they become sick with FIP or not.
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How Does the Vet Diagnose FIP?
There’s no denying it, reaching a definitive diagnosis of FIP is a headache. The problem is there is no one, single test that puts a big red ‘Yes’ in the box next to the question: Is this FIP?
Straight away you can see part of the problem; testing positive for coronavirus doesn’t mean the cat has FIP, it just means the cat has been exposed to a bug that causes diarrhoea. (However a negative test does rule out FIP.)
Diagnosing FIP is like having a 1,000 piece jigsaw puzzle with now ideal of what the finished picture looks like. You have to piece together as many pieces as you can, to build the most likely picture.
The tests a vet uses to piece things together are:
- Clinical signs: a belly full of fluid in a young feverish cat is a pretty heavy hint
- Coronavirus titre: A negative result rules out FIP
- Protein levels: FIP changes the balance of proteins in the blood stream, and high globulins with normal albumin levels are a signpost
- Analysis of abdominal fluid: very high protein levels are suspicious
- High AGP levels: Acid glycoprotein (AGP) can help rule out fluid in the belly due to other causes such as cancer or liver disease
- Inflammatory changes such as iritis
- Antigen tests to look for FIP virus: False negatives are common.
Typically, the vet pulls together as much evidence as possible and gives the most appropriate treatment, and hopes against hope the cat gets better. If they don’t, then FIP becomes even more likely.
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Treatment for FIP
Sadly, survival rates are low. The patient’s main hope rests on interferon, an antiviral drug which stops the virus reproducing and minimises its effects. It seems to help in some cases and can buy extra time others, but it is not a cure.
If you suspect a cat in your household has FIP, or indeed if they have diarrhoea, then keep them away from your other cats and make sure they use a separate litter tray and feeding bowls. A cat with a healthy immune system that is exposed to a low level of virus may be able to fight off FIP and stay well but with so much at stake it’s not worth taking the risk.
I too recently lost my 10 month old kitty to FIP. I never even heard of this disease till 3 weeks ago when the vet suspected it. She was only 9 months when she started to get sick but was a very healthy, very big, very thriving cat so it was a shock to us! We believe it was bought out by stress. 2 weeks prior to her starting to get sick we adopted a new kitten. She was very upset about it but we thought nothing of it at the time. Only that she would eventually accept the new kitten. If i somehow knew she was harbouring such a illness i would of never introduced a new kitten. I live with that guilt every day now. She lived a total of 7 weeks of being sick. Took 4 of those weeks to get her diagnosis and 2 weeks later we had to put her down as her liver was starting to fail and poison her blood. This was the most heartbreaking and devastating thing ever. I still have 3 kitties who were all more than likely exposed and i worry every single day if they are next. FIP is a awful illness.
Last night we took our lovely 8 year old cat to the vet – she was in a bad way – the vet pretty much straight away said it was FIP but, ran tests to be sure – it was confirmed – she would not have made it, so the best for her was to put the poor creature down. We lost another back in November – her brother, he was never tested for this, possibly he may have had that… there is one more, he is doing well so far. Hoping he is safe but, if the others had it then he may too. Its awful as its a wait and see. We also have three more which we have tried to keep divided away, as they are indoor cats. We have been told that it is infectious so again its a wait and see. These boys are coming up to 3 years old. I hope they are well. I really do hope they find a cure for this as soon as possible. It seems more and cats are suffering and dying from this deadly mutated virus.
I lost two kitties within a couple of months a few years ago. It was so heartbreaking. I was reading something the other day about colloidal silver and how someone cured their kitty with it by squirting a dropper full down the kitties throat 4-5 times a day til it got better. I think it took several days. I wish I would have known about that a few years ago. What can it hurt to try something like that when they are on deaths door anyway. I use it on myself. I’m not trying to sell anything but I thought that if someone was looking for an idea of how they could save their kitty from this horrible disease, they might try this. I wish I would have known. I miss my ginger boys.
Thank you! Read your post and tried colloidal silver on our cat with FIP. So far, doing well. He turned around in several days like you said. If we decrease the dose he does seem to get worse but then we amp it up again and he improves. So thankful!
Today I have just lost a cat to this horrible disease, first time I have ever heard of it, he was a feral cat but he was lovely, we thought he had fiu, he died at vet’s so sad xx
A very sad and heartbreaking experience to go through. We just lost our lil Bugatti to FIP. It was horrible to see him go through and so little is known with zero hope. Be proactive if any one of those symptoms appear and see a vet quick. The latest clinical testing seems positive so maybe it will save your cat from this terrible fate. He was 8 months old and a gorgeous seal point Siamese we rescued off the streets. Forever missed…
Wow, FIP is nasty! We’d never heard of this until now, thanks so much for sharing the info.
FIP is a seriously scary disease. We hope that some day, a cure will be found!
Breeders have to be so careful around this, and a really responsible breeder will shut things down and cut the affected lines if it spreads in their cattery. I’m just glad I’m healthy and I come from a cattery where the health has been excellent! I so hope that someday there will be a way to fight this awful condition.
We hope someday that there will be a cure for FIP. This is such a devastating disease.